performance of jaw crushers are given in Table 2 (Hersam, 1923). For calculating the values of K2, the value of Kg for materials like granite and traprock were set equal to one, and the values of KI were calculated with Eq. (10). The variation of K2 with T/G (Table 2) can be represented by the equation K2 = 1.92 x 1 o~.~~~~ (11)